Today, a steady flow of residents in this cold and decaying city visited the dingy staircase where democracy activist Galina Starovoitova was shot dead execution-style last week. They mourned a respected politician -- a rarity in Russia -- and despaired for their city, which has become a shooting gallery for political and gangster violence.

Starovoitova's slaying Friday shook Russia's turbulent political world, a universe beset by fierce ideological rivalries, ethnic baiting, corruption and occasional violence. Some Russian observers characterized the killing as the most shocking since the Stalin-era assassination of the city's Communist Party chief, Sergei Kirov. That shadowy event in 1934 set off a terror campaign by the Soviet government against millions of citizens.

For St. Petersburg, Russia's second city, Starovoitova's death contained an added element of horror. Contract killings have become endemic. Sometimes gangsters are the targets, sometimes politicians. The police record of capturing killers is dismal: No suspect has been arrested in any of the killings. Fyodor Dostoevsky, the 19th-century chronicler of the city's dark side, could have described the situation as "Crime and No Punishment."

The disease of impunity is something St. Petersburg shares with the rest of Russia, where murders almost always go unpunished. The killing of a major politician such as Starovoitova, a member of parliament, creates new worries. The country is entering a two-year period of intense political activity. Parliamentary elections are scheduled for next year; presidential elections are set for 2000, or earlier, if the ailing president, Boris Yeltsin, dies or steps down before then. Some Russians fear that St. Petersburg's problems may foreshadow the nation's.

Today in Moscow, Prime Minister Yevgeny Primakov tried to rally police and intelligence agencies to fight crime and corruption, urging them to "take steps allowing us to calmly advance to elections."

"Criminality as a political force is openly bidding for power for the first time," warned Yuli Rybakov, a colleague of Starovoitova's.

Here in St. Petersburg, crime and politics have done battle for some time. Associates of Starovoitova connect her killing to municipal elections scheduled for next week. She had encouraged democrats to join forces to increase chances of gaining a majority on St. Petersburg's powerful city council. Her feisty manner and steady support for human rights had made her a potent force in the city and her allies were confident.

The election campaign has been rife with foul play. Bogus political parties entered candidates with the same names as standard bearers from authentic parties. The apparent hope is that confused citizens will split their votes between bogus and legitimate candidates, opening the way for the election of unscrupulous rivals.

At stake here, as elsewhere in Russia, are property and resources still in the grip of government. Law enforcement officials say that the city is a battleground of mafia groups vying for control of the port, commercial real estate, banking and contracts to supply fuel oil to the city. The persistent violence has hindered foreign investment and scared Russians away from doing legitimate business.

In the past two months, three officials associated with city hall and an oil tycoon with municipal connections were killed, sometimes by imaginatively gruesome means.

In October, for instance, someone planted a pound of dynamite in a lamp at the entrance of oil executive Dmitri Filipov's apartment in central St. Petersburg. He died in the explosion. Filipov was a former Communist Party functionary and city tax collector who had founded a company that won an exclusive contract to supply fuel to city transport agencies. He also was in control of a conglomerate with holdings in gasoline enterprises; he took over after its previous director was gunned down.

His killing followed the September death of Yevgeny Agaryov, deputy head of the city consumer committee. Agaryov was felled by a remote-controlled bomb attached to his apartment balcony. Among his duties was regulation of city cemeteries -- another prized target of gangsters, police say.

Until Starovoitova's death, the city's most prominent victim was Mikhail Manevich, the overseer of municipal property. Last year, a sniper killed him as he drove onto Nevsky Prospect, St. Petersburg's main commercial street.

No one paying homage to Starovoitova today at her apartment building believed the police will catch the criminals. "This is a political murder and political murders are not solved in Russia," said Yelena Lebedeva, an engineer. "Our city will not smile again for a long time."

"Look, by now, probably the killers themselves are dead. That's the way things go in Russia," said Mikhail Radimushkin, a journalist. "Our police are also remarkably incompetent in these matters."

Today, the walls were still blood-stained below the landing where an armed man and woman approached Starovoitova and an aide, Ruslan Linkov. The assailants shot each first with an automatic weapon. A silencer muffled the shots. Then the killers fired at the head of each victim with a Beretta pistol. Starovoitova died instantly, but Linkov survived. He phoned a news agency to report the shootings before passing out. He has since regained consciousness at a St. Petersburg hospital.

Since the killing, mourners have placed carnations and messages of respect to Starovoitova on the stairwell. On the wall, someone pasted a statement Starovoitova made in 1990, when the city was afire with democratic activism and alive with the prospects of freedom. "It's wonderful that the voices of change are being heard," she said. "Let's praise our great city, a center of world culture, the capital of spirit and the transmitter of Russian ideas." CAPTION: A woman places a candle in front of the apartment house of Galina Starovoitova, the democracy activist murdered there last week. ec